Update version to 1.0.0
Purge notifications issue resolved in phpBB
Rename version update migration file
Make header link optional
Fix a docblock missing a param
Test header link when enabled and disabled
Install header link option on by default
Drop the version definition from the ACP info file

These are not used in phpBB, so we might as well be the first to stop using them (a ticket has been submitted t remove them from the core too).
Adjust version to beta 1
Remove version from database storage
Fix migration class rename
Merge pull request #107 from VSEphpbb/updates

Update version and other small fixes